The present invention relates generally to control systems for internal combustion engines, and more particularly, to an electronic throttle spring torque adaptation system.
Many previously known motor vehicle throttle control systems have a direct physical linkage between an accelerator pedal and the throttle body so that the throttle plate is pulled open by the accelerator cable as the driver presses the pedal. The direct mechanical linkages include a biasing force that defaults the linkages to a reduced operating position, in a manner consistent with regulations. Nevertheless, such mechanisms are often simple and unable to adapt fuel efficiency to changing traveling conditions. Moreover, these mechanisms add significant weight and components to the motor vehicle.
An alternative control for improving throttle control and the efficient introduction of fuel air mixtures into the engine cylinders is presented by electronic throttle control. The electronic throttle control includes a throttle control unit that positions the throttle plate by an actuator controlled by a microprocessor based on the current operating state determined by sensors. The processors are often included as part of a powertrain electronic control that can adjust the fuel air intake and ignition in response to changing conditions of vehicle operation as well as operator control.
Typical electronic throttles include a biasing spring coupled to a throttle plate. The spring torque generated by this biasing spring is opposed by controlling a throttle plate actuator with a current (or voltage or H-driver duty cycle) to achieve the desired throttle plate position. Desired throttle plate position may be achieved by treating the spring torque as a disturbance torque and letting the integrator wind up to the required mean value necessary to oppose it. Unfortunately, treating the spring torque as a disturbance torque works poorly where the spring torque varies with throttle angle. To compensate for this, many systems resort to storing an invariant estimate of spring torque or spring torque variation in a look-up table.
The disadvantages associated with these conventional electronic throttle idle control techniques have made it apparent that a new technique for opposing electronic throttle spring torque is needed. The new technique should operate without dependence on an estimate of spring torque or spring torque variation. The present invention is directed to these ends.
It is, therefore, an object of the present invention to provide an improved and reliable electronic throttle spring torque adaptation system. Another object of the invention is to provide an electronic throttle control system that operates without dependence on an estimate of spring torque or spring torque variation.
In accordance with the above and other objects of the present invention, an electronic throttle spring torque adaptation system is provided. In one embodiment of the invention, a method for controlling a positioning device of an internal combustion engine includes providing an electric motor for actuating the positioning device. The electric motor actuates the positioning device against the spring bias torque. A first current is supplied to the electric motor to move the motor to an actual position. The actual position of the motor is then compared to a requested position. The first current is monitored to determine the required current to oppose the spring torque at the actual position. The requested position is summed with a spring opposition term based upon the required current into a adjusted requested position. Finally, current is supplied to the electric motor to move the motor to an adjusted requested position.
The present invention thus achieves an improved electronic throttle spring torque adaptation system. The present invention is advantageous since it automatically adjusts the controller for changes in electronic throttle spring torque.
Additional advantages and features of the present invention will become apparent from the description that follows, and may be realized by means of the instrumentalities and combinations particularly pointed out in the appended claims, taken in conjunction with the accompanying drawings.